Olefin polymerization

ABSTRACT

A process for producing a novel-highly active lanthanide containing catalyst comprising the product formed by admixing a lanthanide hydroxyhalide and an electron donor bidentate organic ligand chosen from among diamines, dihydric alcohols, and diketones with an organoaluminum cocatalyst component and its use in the polymerization of olefins, especially olefins such as ethylene and 1,3-butadiene.

This application is a divisional of application Ser. No. 650,034, filedSept. 13, 1984 now allowed.

BACKGROUND OF THE INVENTION

This invention relates to a process for producing olefin polymers and toa high activity catalyst suitable for use in the process. The presentinvention relates to a catalyst, the method for making the catalyst, anda polymerization process for employing the catalyst.

In accordance with one aspect, this invention relates to an improvedolefin polymerization catalyst produced by admixing a rare earth metalhydroxyhalide and a bidentate organic ligand containing from 2 to about20 carbon atoms selected from among diamines, diols and diketones.Diamines are presently preferred. ln accordance with another aspect,this invention relates to a catalyst system comprising alanthanide-containing catalyst component and a cocatalyst comprising anorganoaluminum compound. In accordance with still another aspect, thisinvention relates to the formation of olefin polymers from conjugateddienes, vinyl monomers, and alpha-olefins in the presence of a rareearth metal hydroxyhalide-containing catalysts produced as set forthherein.

It is old in the field of olefin polymerization to prepare solidpolymers by employing catalyst systems comprising a transition metalcompound and an organometallic cocatalyst. It is also known that theproductivity of such catalyst can generally be improved if thetransition metal compound is employed in conjunction with another metalcompound. Many of the prior art catalyst systems are relatively low inactivity and, as a result, research continues in an effort to improvethe catalyst systems with respect to production of olefin polymers. Thepresent invention is concerned with new high productivity catalystswhich employ rare earth metal hydroxyhalide as one of the components ofthe catalyst for the production of polymers from olefins.

Accordingly, an object of this invention is to provide an improvedpolymerization catalyst.

A further object of this invention is to provide an improved process forthe production of olefin polymers.

Other objects, aspects, as well as the several advantages of theinvention will be apparent to those skilled in the art upon reading thespecification and the appended claims.

SUMMARY OF THE INVENTION

In accordance with the invention, a lanthanide-containing catalystcomponent is produced by admixing a rare earth metal hydroxyhalide and abidentate organic ligand under such conditions that a suspension orcomplex of these materials is obtained.

In accordance with another embodiment of the invention, alanthanide-containing catalyst component comprising a rare earth metalhydroxyhalide-bidentate organic ligand is combined with anorgano-aluminum co-catalyst component to form a catalyst compositionsuitable for the polymerization of olefins.

Further in accordance with the invention, olefins and especiallyalpha-olefins and conjugated dienes are polymerized under polymerizationconditions employing the above catalyst.

DETAILED DESCRIPTION OF THE INVENTION

The lanthanide-containing component (component A) of the polymerizationcatalyst of the invention is formed from a rare earth metalhydroxyhalide and an electron donor bidentate organic ligand.

Thus, in accordance with the invention, an active catalyst forpolymerizing alpha-olefins, conjugated dienes and vinyl monomerscomprises a rare earth metal hydroxyhalide associated with at least oneelectron donor bidentate organic ligand selected from among diamines,dihydric alcohols and diketones. This catalyst component is used with acocatalyst comprising at least one organoaluminum compound (componentB).

The rare earth metal hydroxyhalide of catalyst component A can compriseany one of the rare earth metals of the lanthanide series, includingthose metals of atomic number ranging from 57-71.

The lanthanide-containing catalyst component can be produced underconditions such that a suspension of the component is formed by admixinga bidentate ligand, a solvent or diluent and a rare earth metalhydroxyhalide (hydroxide halide). The meta- hydroxyhalide can beexpressed as Ln(OH)_(a) X_(3-a) where Ln is a rare earth metal such asLa, Ce, Pr, Nd, Sm, Gd, Tb, Dy and Ho, generally Nd or Pr, X is ahalogen atom, usually chlorine, and a can vary from about 0.1 to about2.9. Neodymium is the presently preferred rare earth metal.

The electron donor bidentate ligand employed according to the inventioncomprises any organic compounds having from 2 to about 20 carbon atomsselected from among diamines, dihydric alcohols, and diketones.

The bidentate ligand employed is preferably an aliphatic diamine,usually selected from among the ethyleneamine and propyleneaminefamilies. However, an aromatic diamine can be used. Specific examplesinclude: ethylenediamine (presently preferred), diethylenetriamine,triethylenetetraamine, 1,2-propanediamine, 1,3-propanediamine,1,4-butanediamine, hexamethylenediamine, 1,20-eicosanediamine,p-phenylene diamine, and the like and mixtures.

Another group of ligands that can be used comprise organic compoundscontaining the divalent carbonyl group (C═O) present in 1,2-diketones,1,3-diketones and 1,4-diketones containing from 2 to about 20 carbonatoms per radical. Exemplary compounds include 2,3-butanedione,4,5-octanedione, 2,4-pentanedione (acetylacetone), 2,4-hexanedione,3-ethyl-2,4-pentanedione, 5,5-dimethyl-1-3-cyclohexanedione,2,5-hexanedione, 6-methyl-2,5-heptanedione, 2,5-octadecanedione, and thelike and mixtures.

Still another group of organic compounds that can be used include thosecontaining hydroxyl groups present in dihydric alcohols such as diols,glycols, glycol ethers, and the like. The ligand is one selected from adihydric alcohols containing from 2 to about 20 carbon atoms, preferablyan alkylene glycol containing about 6 to 16 carbon atoms and analiphatic ether of alkylene glycols containing from 2 to about 6 carbonatoms. Examples of the dihydric alcohols include 1,2-ethanediol,1,2-propanediol, 1,3-propanediol, 1,4-hexanediol, 1,10-decanediol,1,12-dodecanediol, 1,2-hexadecanediol and 1,20-cicosanediol. Example ofethers derived from alkylene glycols include 2-ethoxyethanol (glycolmonoethyl ether or ethylk cellosolve), 2-butoxyethanol,2-phenoxyethanol, monoethyl ether of diethyleneglycol (ethyl carbitol),diethyl ether of diethylene glycol (diethyl carbitol) and the like andmixtures.

The mole ratio of bidentate ligand to lanthanide can range from about 1to about 10, preferably from about 3 to about 7.

The complex can be formed at temperatures ranging from about 25° toabout 150° C., preferably from about 60° to abut 100° C. at reactiontime ranging from about 1 minute to about 72 hours, preferably fromabout 10 minutes to about 24 hours.

The amount of solvent or diluent employed in the formation of thecomplex is generally within the range of about 5 to about 300 grams ofsolvent per gram of rare earth metal hydroxyhalide.

Typical solvents or diluents, include the normally liquid hydrocarbonshaving 3 to 12 carbon atoms such as propane, cyclohexane, n-heptane,methylcyclohexane, toluene, xylenes, and the like, and mixtures.

The components used to prepare catalyst component A (Step 1) can bemixed in any order. For example, any two components can be mixed priorto introduction of the third component. It is likewise within the scopeof this invention to combine all components simultaneously in a reactor.

The lanthanide-containing catalyst components described above can becombined with an organoaluminum compound (Step 2) to form an activecatalyst effective for the polymerization of olefins.

The organoaluminum compound used in step 2 of the catalyst formation canbe a compound having the formula

    AlR.sub.n X.sub.3-n

wherein R is a hydrocarbyl radical containing 1 to about 20 carbonatoms, X is a hydrogen, halogen, preferably chlorine or bromine, oralkoxide having 1-20 carbon atoms, and n is a number of 1 to 3. Thussuitable types of organoaluminum compounds are selected fromtrihydrocarbylaluminum, dihydrocarbylaluminum halide,hydrocarbylaluminum dihalide, dihydrocarbylaluminum hydride,dihydrocarbylaluminum alkoxide, hydrocarbylaluminum dialkoxide and thelike, and mixtures thereof.

Examples of suitable specific organoaluminum compounds that can be usedaccording to the invention include triethylaluminum,triisobutylaluminum, diethylaluminum hydride, diisobutylaluminumhydride, diethylalumihum chloride, diisobutylaluminum chloride, and thelike, and mixtures thereof.

The organoaluminum compound can be combined with a solution of theproduct of step 1. Preferably, the hydrocarbon solution of theorganoaluminum compound is combined with a solution of the product ofstep 1.

The organoaluminum cocatalyst is used in amounts ranging from about 10to about 200 moles per mole of lanthanide hydroxyhalide and in apreferred range of 20 to about 40 moles per mole of lanthanidehydroxyhalide. It should be noted that each mole of ligand in thecatalyst inactivates one mole of organoaluminum cocatalyst and,therefore, higher amounts of ligand will require higher amounts oforganoaluminum cocatalyst. Thus, the mole ratio of organoaluminumcocatalyst to ligand is at least one and will preferably be in the rangeof about 2/1 to about 20/1 moles of organoaluminum per mole of ligandassociated with the lanthanide hydroxyhalide.

The temperatures employed in step 2 can vary over a wide range,generally being in the range of about 0° to about 150° C., andpreferably about 25°-80° C. Following the combination of theorganoaluminum compound and the solution of step 1, the composition isgenerally stirred or agitated for a sufficient time to insure completemixing of the components, e.g., a few minutes to about 2 hours. Afterstirring is discontinued, the solids product is recovered by filtrationor decantation, washed with a dry hydrocarbon such as n-heptane, etc.,to remove any soluble material that may be present and optionally dried.

Suitable as the olefins which can be used herein are ethylene, andhigher 1-olefins such as propylene, butene-1, hexene-1, and the like,vinyl monomers such as styrene and conjugated diolefins, such asbutadiene, isoprene, trans-1,3-pentadiene,trans-2-methyl-1,3-pentadiene, trans-trans-2,4-hexadiene,2,3-dimethylbutadiene, and the like, and mixtures containing 2 or morepolymerizable unsaturated hydrocarbons as enumerated above. A particulargroup of olefins to be polymerized according to the invention includesunsaturated hydrocarbons having 2 to 6 carbon atoms and having at leastone polymerizable ethylenic double bond.

These polymerizable monomers are polymerized by use of a catalystcomposition of the present invention whereby a polymer with the variousproperties depending on the type of catalyst, monomer(s), andpolymerization conditions employed, e.g., the type of solvent,polymerization temperature, polymerization pressure, etc., is obtained.Further, not only homopolymers can be produced from the polymerizableunsaturated monomer but also copolymers can be produced by employing aplurality of said monomers in accordance with the process of the presentinvention.

The polymerization reaction by use of a catalyst composition of thepresent invention can be carried out in the presence of a solvent or adiluent with advantages. Suitable as the solvent for the instantreaction system are inert hydrocarbons, or halogenated hydrocarbons,e.g., butane, pentane, hexane, heptane, isooctane, cyclohexane,methyl-cyclohexane, benzene, toluene, xylene, tetralin, decalin, andother aliphatic, alicyclic, aromatic hydrocarbons, or mixtures thereof,or petroleum fractions free from polymerizable unsaturation,tetrachloro-ethylene, chlorobenzene, o-dichlorobenzene, and the like.

The process for polymerizing olefins by use of a catalyst composition ofthe present invention can be carried out in a batch type,semi-continuous type, or continuous type reactor. Polymerizationpressure can vary depending on the type of monomer, the catalyticactivity of the catalyst system, the desired degree of polymerization,etc. Generally, the present polymerization reaction can be carried outat a temperature in the range of about 0° to about 200° C., preferably atemperature of about 25° to about 100° C. Polymerization pressure can besubatmospheric or superatmospheric pressure up to about 300 atmospheresand preferably from atmospheric pressure to about 100 atmospheres.

Polymerization can be carried out in gas phase in the absence of asolvent or a diluent. In a presently preferred mode of operation,however, polymerization is accomplished in the presence of a solvent ordiluent which is liquid under the reaction conditions employed.

Generally, when using a solvent or diluent in the instant polymerizationreaction, it is convenient to introduce olefin into a dispersioncontaining the catalyst of the present invention in the solvent ordiluent. The catalyst composition can be added in its whole amount tothe polymerization system at the start of the polymerization or it canbe added portion-wise over the period for the polymerization.

In order to carry out the present invention by a continuous orsemi-continuous process, the contact between catalyst and monomer can beeffected by various ways. For example, the olefin can be contacted withthe catalyst in the form of a fixed bed, a slurry, a fluid bed, or amovable bed.

In order to recover a produced polymer from the polymerization system,the crude polymerization product is, for example, taken up and subjectedto solvent extraction, hot filtration under a pressure or centrifugalseparation to yield a substantially pure polymeric product. A selectionof the polymerization conditions for the process of the presentinvention, as well as the method for the recovery and purification ofthe polymeric product will be understood by those skilled in the artfrom the conventional low or modest pressure polymerization processesfor olefins.

The following examples will serve to show the present invention indetail by way of illustration and not by way of limitation.

EXAMPLE I

Neodymium hydroxychloride, 0.47 g (2.2 mmole), having the formulaNd(OH)₂.4 Cl₀.6 and 0.60 g (10 mmole) of ethylene diamine (ED) weremixed with 10 mL (7.7 g) of cyclohexane at reflux temperature overnight.One mole Nd compound was associated with about 5 moles of ED. The weightratio of solvent to Nd compound was about 16 to 1. Individual portionsof the resulting suspension (0.5 mL, equivalent to about 0.1 matom ofNd) was employed with an organoaluminum compound as cocatalyst in thepolymerization of 1,3-butadiene.

A polymerization vessel was charged with 200 mL of solvent (cyclohexaneor toluene), 16 g of 1,3-butadiene to give a calculated 0.625 mmolecatalyst per 100 parts by weight monomer (MHM), and organoaluminumcompound (variable) as cocatalyst. The polymerization system wasagitated in a constant temperature bath at 50° C. for 3 hours or 19hours, as specified. Polymerization was terminated by the addition ofabout 2 parts by weight of butylated hydroxytoluene per 100 parts byweight of polymer. The polymer was recovered by coagulation inisopropanol and drying in vacuo overnight at 60° C. The organoaluminumcompounds employed as cocatalysts and the polymerization resultsobtained are set forth in Table 1.

                                      TABLE 1                                     __________________________________________________________________________                            Run                                                   Run       Cocatalyst    Time                                                                             Conv.                                                                             Cis.sup.a                                                                        Intrinsic                                                                          Gel.sup.b                              No.                                                                              Solvent                                                                              Type  MHM mmole                                                                             Hrs.                                                                             %   %  Viscosity                                                                          %                                      __________________________________________________________________________    1  cyclohexane                                                                          .sup. TEA.sup.c                                                                     19  3.1  3 89  97 10.1 35                                     2  cyclohexane                                                                          TEA   46  7.75                                                                               3 89  97  7.73                                                                              43                                     3  toluene                                                                              TEA   19  3.1 19 32  95 6.2  6                                      4  toluene                                                                              TEA   46  7.75                                                                              19 21  94 5.6  4                                      5  toluene                                                                              DEALH.sup.d                                                                         13  2.24                                                                              19 29  97 5.5  7                                      6  toluene                                                                              DEALH.sup.                                                                          34  5.6 19 27  96 4.3  4                                      7  toluene                                                                              DIBALH.sup.e                                                                        15  2.44                                                                              19 28  97 6.2  6                                      __________________________________________________________________________     .sup.a Cis configuration in polymer determined as in U.S. 3,278,508 col.      20 lines 71 ff, col. 21 lines 1-21.                                           .sup.b Inherent viscosity and gel determined as in U.S. 3,278,508 col. 20     notes a and b                                                                 .sup.c triethylaluminum                                                       .sup.d diethylaluminum                                                        .sup.e diisobutylaluminum hydride                                        

The results in Table 1 show that polybutadiene with high cis-1,4configuration having medium to high viscosity was prepared with theinventive catalysts. The difference in choice of reaction medium,cycloparaffin or aromatic hydrocarbon, upon conversion effected, gelformed and intrinsic viscosity is seen in comparing the results obtainedin runs 1, 2 with cyclohexane as the solvent and in runs 3-8, withtoluene as the solvent. ln cyclohexane, conversion is approximatelytripled at about 1/6 the reaction time, inherent viscosity is increasedfrom about 5 to 10 times, relative to the results obtained in a toluenesolvent.

EXAMPLE II (Control)

Catalysts comprising neodymium hydroxide associated with ethylenediamine were prepared in the manner described before. Catalyst A wasmade by employing 0.47 g (2.4 mmoles) of Nd(OH)₃, 0.60 g (10 mmoles) ofED and 10 mL of cyclohexane. The resulting complex had a calculatedcomposition of Nd(OH)₃ 4 ED. Catalyst B was made by employing 0.47 g(2.4 mmoles) of Nd(OH)₃, 0.90 g (15 mmoles) of ED and 10 mL ofcyclohexane. The resulting complex had a calculated composition ofNd(OH)₃ 6.2 ED. As before, 0.5 mL portions of catalyst, equivalent toabout 0.1 matom of Nd, was employed with an organoaluminum compound ascocatalyst in the polymerization of 1,3-butadiene.

Catalyst A, 0.1 mmole of Nd(OH)₃ 4 ED was employed in separatepolymerization runs with 16 g of 1,3-butadiene and 3.1 mmole of TEA andwith 7.75 mmole of TEA as cocatalyst in 200 mL of cyclohexane for 24hours at 50° C. No polymer was formed in either run.

Similarly, catalyst B, 0.1 mmole of Nd(OH)₃ 6.2 ED was employed with10.8 mmole of TEA as cocatalyst in 200 mL of cyclohexane and 16 g of1,3-butadiene in a 20 hour polymerization run at 50° C. No polymer wasformed.

These runs illustrate that complexes of Nd(OH)₃ and ethylenediamine inthe absence of halide are inactive for the polymerization of1,3-butadiene under the conditions used.

We claim:
 1. A polymerization catalyst system comprising(1) a catalystcomponent A formed by admixing a rare earth metal hydroxyhalide and anelectron donor bidentate organic ligand having from 2 to about 20 carbonatoms selected from among diamines, dihydric alcohols, and diketones,and (2) a cocatalyst component B comprising an organoaluminum compound.2. A catalyst according to claim 1 wherein the mole ratio of ligand torare earth metal hydroxyhalide ranges from about 1 to about
 10. 3. Acomposition according to claim 1 wherein said organoaluminum cocatalystcomponent is present in amounts ranging from about 10 moles to about 200moles per mole of rare earth metal hydroxyhalide,
 4. A compositionaccording to claim 2 wherein said hydroxyhalide has the formula

    Ln(OH).sub.a X.sub.3-a

wherein Ln is a rare earth metal, X is a halogen, and a ranges fromabout 0.1 to about 2.9, and said ligand is an aliphatic or aromaticpolyamine.
 5. A composition according to claim 4 wherein said rare earthmetal hydroxyhalide is neodymium hydroxychloride, said ligand isethylenediamine, and said cocatalyst is one of diethylaluminum hydride,triethylaluminum, triisobutylaluminum, or diisobutylaluminum hydride. 6.A process for producing a catalyst for the polymerization of olefinscomprising(1) combining a rare earth metal hydroxyhalide and an electrondonor bidentate organic ligand having from 2 to about 20 carbon atomsselected from among diamines, dihydric alcohols, and diketones in aninert liquid diluent under conditions to form a complex, and (2)contacting the product of (1) with an organoaluminum compound to form apolymerization catalyst system in which the mole ratio of organoaluminumcompound to rare earth metal hydroxyhalide ranges from about 10 to about200 moles per mole and a mole ratio of ligand to rare earth metalranging from about 1 to about
 10. 7. A process according to claim 5wherein the conditions under which said hydroxyhalide and ligand arecontacted ranges from about 25° to about 150° C.
 8. A process accordingto claim 7 wherein the organoaluminum cocatalyst is one of atrihydrocarbylaluminum, dihydrocarbylaluminum halide,hydrocarbylaluminum dihalide, dihydrocarbylaluminum hydride,dihydrocarbylaluminum alkoxide, and hydrocarbylaluminum dialkoxide.
 9. Aprocess according to claim 6 wherein said hydroxyhalide has the formula

    Ln(OH).sub.a X.sub.3-a

wherein Ln is a rare earth metal, X is a halogen, and a ranges fromabout 0.1 to about 2.9 and said ligand is an aliphatic or aromaticpolyamine.
 10. A process according to claim 9 wherein said hydroxyhalideis neodymium hydroxychloride of the formula Nd(OH)₂.4 Cl₀.6, said amineis ethylenediamine, and said diluent is cyclohexane.
 11. A processaccording to claim 10 wherein said organoaluminum cocatalyst isdiethylaluminum hydride, diisobutylaluminum hydride, or triethylaluminumor triisobutylaluminum.